The present invention is related to systems and methods for reducing cross coupling in proximate signal lines, and in particular to systems and methods for moderating the slew rate of one or more signals.
Typical electronics products include connectors where two or more signal lines are located adjacent to one another. Cross coupling between the proximate signal lines is possible in such cases, with the amount of cross coupling varying as a function of the distance between the proximate signal lines and the rate at which the proximate signal lines are switching. This relationship is described by the following equation:I=C*dV/dt. 
In many cases, any cross coupling may simply be ignored or filtered. However, in some cases, it may be desirable to minimize the occurrence of cross coupling. This minimization may be achieved by moving two signals associated with the cross coupling farther from one another, thus reducing the value of C in the aforementioned equation. This approach, however, may be impractical where space is at a premium, or where conformance with a standard form factor is required. Another solution for reducing the cross coupling is to limit the rate at which the proximate signal lines are switching. This may be achieved by applying the signal to an RC network. Such an RC network, however, provides for a substantially non-constant slew rate as defined by the following equation:V=e(−t/RC).In some cases, this substantially variable slew rate is undesirable.
As a concrete example, it is common for a fly height driver signal and a read signal in a disk drive connector to be located very close to one another due to standardized layout specifications. Because of this proximity and the rate at which the fly height driver signal switches, it is possible to have very substantial cross coupling between the signals. For example, in one case the capacitance (C) between the read signal line and the fly height driver signal line may be one picofarad, and the fly height driver signal line may be switching a one volt signal with a one hundred picosecond rise time. Using the aforementioned equation, the cross coupling induced current between read signal and the fly height driver signal is approximately ten milliamps. Such a substantial current can result in a reliability reduction.
Hence, for at least the aforementioned reasons, there exists a need in the art for advanced systems and methods for reducing cross coupling between proximate signals.